Additive manufacturing of heat exchangers in aerospace applications: a review

The current review is mainly focused on exploring Additive Manufacturing (AM) methods suitable for the fabrication of complex-shaped compact Heat Exchangers (HXs) used in the aerospace industry. The introduction of Additive Manufacturing technologies, thanks to the freedom of design and the ability to produce topologically optimised complex parts, aims at the production of high-efficiency Heat Exchangers. These new Heat Exchangers are characterised by very thin features and a substantial reduction in the weight of the parts compared to the products conventionally manufactured, maintaining a leak-proof structure and excellent mechanical properties. The current L-PBF systems along with software packages are not yet fully ready for the creation of thin leak-proof features needed for highly efficient complex-shaped compact Heat Exchangers and most of the studies in the literature are in the initial development stages. This literature review is covering the current advanced manufacturing technologies which can be employed to manufacture the new generation of compact Heat Exchangers, with particular reference to the Laser-Powder Bed Fusion. The advantages and the current challenges of the Additive Manufacturing processes are described. Furthermore, the state-of-art of topological optimisation and CFD analysis as design tools to support the production of additively manufactured were critically analysed. Finally, new criteria of how to down-select compact Heat Exchanger materials for Additive Manufacturing in the aerospace industrial sector are presented, with particular attention to Aluminium alloys.